{"id":"CVE-2026-43215","state":"PUBLISHED","title":"cifs: Fix locking usage for tcon fields","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix locking usage for tcon fields\n\nWe used to use the cifs_tcp_ses_lock to protect a lot of objects\nthat are not just the server, ses or tcon lists. We later introduced\nsrv_lock, ses_lock and tc_lock to protect fields within the\ncorresponding structs. This was done to provide a more granular\nprotection and avoid unnecessary serialization.\n\nThere were still a couple of uses of cifs_tcp_ses_lock to provide\ntcon fields. In this patch, I've replaced them with tc_lock.","publishedAt":"2026-05-06T11:28:17.425Z","updatedAt":"2026-10-30T12:25:11.274Z","severity":{"score":8.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"92d197ef7e9bb4994dae2bb17c2f19fa09d219a2","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"953953abb66e52c224057ab91e404284fefeab62","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"601dd3b79769b38d30b693c40afdb2a4b7edf9d0","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"3969db6b22e3d90d8c5f22ac1a7fe0350a94c136","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"8c59eeeeffa1524ef57e173a89a1a3ff539888d5","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"96c4af418586ee9a6aab61738644366426e05316","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/cached_dir.c","fs/smb/client/smb2misc.c","fs/smb/client/smb2ops.c","fs/smb/client/smb2pdu.c","fs/smb/client/trace.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.0","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.128","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/cached_dir.c","fs/smb/client/smb2misc.c","fs/smb/client/smb2ops.c","fs/smb/client/smb2pdu.c","fs/smb/client/trace.h"]}],"references":["https://git.kernel.org/stable/c/92d197ef7e9bb4994dae2bb17c2f19fa09d219a2","https://git.kernel.org/stable/c/953953abb66e52c224057ab91e404284fefeab62","https://git.kernel.org/stable/c/601dd3b79769b38d30b693c40afdb2a4b7edf9d0","https://git.kernel.org/stable/c/3969db6b22e3d90d8c5f22ac1a7fe0350a94c136","https://git.kernel.org/stable/c/8c59eeeeffa1524ef57e173a89a1a3ff539888d5","https://git.kernel.org/stable/c/96c4af418586ee9a6aab61738644366426e05316"],"weaknesses":["CWE-362"],"ingestedAt":"2026-10-30T12:42:04.495Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2026/43xxx/CVE-2026-43215.json","commit":"db8103c5921aac81d5d90efcf3745980dafabf49","baselineCommit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-43215","state":"PUBLISHED","datePublished":"2026-05-06T11:28:17.425Z","dateUpdated":"2026-10-30T12:25:11.274Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2026-05-01T14:12:55.993Z"},"containers":{"cna":{"title":"cifs: Fix locking usage for tcon fields","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ncifs: Fix locking usage for tcon fields\n\nWe used to use the cifs_tcp_ses_lock to protect a lot of objects\nthat are not just the server, ses or tcon lists. We later introduced\nsrv_lock, ses_lock and tc_lock to protect fields within the\ncorresponding structs. This was done to provide a more granular\nprotection and avoid unnecessary serialization.\n\nThere were still a couple of uses of cifs_tcp_ses_lock to provide\ntcon fields. In this patch, I've replaced them with tc_lock."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"92d197ef7e9bb4994dae2bb17c2f19fa09d219a2","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"953953abb66e52c224057ab91e404284fefeab62","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"601dd3b79769b38d30b693c40afdb2a4b7edf9d0","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"3969db6b22e3d90d8c5f22ac1a7fe0350a94c136","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"8c59eeeeffa1524ef57e173a89a1a3ff539888d5","versionType":"git"},{"version":"d7d7a66aacd6fd8ca57baf08a7bac5421282f6f8","status":"affected","lessThan":"96c4af418586ee9a6aab61738644366426e05316","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/cached_dir.c","fs/smb/client/smb2misc.c","fs/smb/client/smb2ops.c","fs/smb/client/smb2pdu.c","fs/smb/client/trace.h"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.0","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.0","versionType":"semver"},{"version":"6.1.191","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.128","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.75","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.18.16","status":"unaffected","lessThanOrEqual":"6.18.*","versionType":"semver"},{"version":"6.19.6","status":"unaffected","lessThanOrEqual":"6.19.*","versionType":"semver"},{"version":"7.0","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/smb/client/cached_dir.c","fs/smb/client/smb2misc.c","fs/smb/client/smb2ops.c","fs/smb/client/smb2pdu.c","fs/smb/client/trace.h"]}],"references":[{"url":"https://git.kernel.org/stable/c/92d197ef7e9bb4994dae2bb17c2f19fa09d219a2"},{"url":"https://git.kernel.org/stable/c/953953abb66e52c224057ab91e404284fefeab62"},{"url":"https://git.kernel.org/stable/c/601dd3b79769b38d30b693c40afdb2a4b7edf9d0"},{"url":"https://git.kernel.org/stable/c/3969db6b22e3d90d8c5f22ac1a7fe0350a94c136"},{"url":"https://git.kernel.org/stable/c/8c59eeeeffa1524ef57e173a89a1a3ff539888d5"},{"url":"https://git.kernel.org/stable/c/96c4af418586ee9a6aab61738644366426e05316"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","baseScore":8.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable CIFS/SMB client code is exercised through SMB protocol activity with a remote server, including DFS referral handling, reconnects, cancelled closes, and cached directory lease cleanup. A malicious or compromised SMB server can influence these network-driven paths after a client connects.\nAC:L - The issue is a locking/refcount race, but the remote SMB peer can repeatedly trigger reconnects, delayed/cancelled responses, DFS behavior, and lease/cached-directory activity to exercise the affected paths. There is no rare configuration or uncontrollable one-shot condition required beyond a CIFS mount being in use.\nPR:N - The attacker does not need privileges on the vulnerable client system; they can act as the SMB server or network peer providing crafted behavior to the CIFS client. Although mounting CIFS locally is privileged, that is victim-side setup/user interaction rather than attacker privileges on the impacted host.\nUI:R - Exploitation requires the client system to mount or otherwise use an SMB/CIFS share, which is a victim/user or administrator action. Once connected, the malicious server can drive the vulnerable network paths.\nS:U - The impact is within the same Linux kernel security authority running the CIFS client. This is standard kernel memory corruption/panic potential, not a VM escape or cross-authority boundary bypass.\nC:H - The inconsistent locking can corrupt the tcon reference count and allow use-after-free of `struct cifs_tcon`. Kernel UAF conditions are reasonably capable of being shaped into memory disclosure primitives.\nI:H - The same premature free and later dereference/use of the tcon object creates kernel heap use-after-free memory corruption. Under the required higher-severity rule, this is treated as potentially exploitable for arbitrary write or control-flow compromise.\nA:H - At minimum, refcount corruption and use-after-free of a live CIFS tcon can lead to kernel oops, panic, or hangs in reconnect/close/DFS workqueue paths. The condition can be triggered repeatedly by malicious SMB server behavior while the share is mounted."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-10-30T12:25:11.274Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.1.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.6.128"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.12.75"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.18.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"6.19.6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.0","versionEndExcluding":"7.0"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"id":"CVE-2026-43215","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:15:53.438726Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-362","lang":"en","type":"CWE","description":"CWE-362 Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2026-10-19T19:16:24.731Z"}}]}}}